There is a significant correlation between dietary supplements of eicosapentaenoic acid (EPA), with reduced incidence of coronary heart disease, selective killing of certain cancer cells and relief of symptoms of rheumatoid arthritis. We propose a biotechnological approach for the production of EPA containing oil from microorganisms grown in controlled, fermentation culture as an alternative to the fish oil form of EPA presently available. The oil produced by the microorganisms selected in Phase I had a higher EPA content, enhanced stability upon heating, and no "fishy" odor when compared to commercially available fish oil sources such as MaxEPA. The strain selection and culture improvement strategies outlined in this proposal should provide the foundation for the economically feasible production of EPA-containing oil using conventional fermentation technologies. Furthermore, the bioproduction of EPA from these microorganisms offers a significant bonus in being able to produce labelled EPA for clinical research in the near term. Our overall goal, is to produce a superior EPA- containing oil which is compatible with, and can be integrated into, typical food products in our diet so that the positive attributes of EPA can be realized by more Americans without the requirement of taking pills.